'04 Yukon XL Denali - Body Control Module Experts?

['63GENIII]

I usually spend my time in the 60 - 66 section so Im new to this area. I thought I'd come next door and see if you guys might have any insight to a persisting intermittent problem that Im having with the Wife's 04 Yukon XL. We got this car in '08 with 50k on it. It has 105 on the clock now and has been a great car with the exception of one problem that it has had almost from day 1. For some reason, there is an intermittent current draw which I have not been able to find the source of. I believe that it may be the BCM because of the other little weird electrical issues that arise when this has happened in the past. It leaves the battery unable to start the car sometimes as little as 4 -5 hours after it has run and on occasion it has taken over night to kill it. The weird symptoms include AC issues like blowing hot air through the defrost when AC should be blowing cold from vents, dome light coming on for no reason, seats adjusting to different positions automatically and a few other things.
To date, I have tried using my VOM to see how much current is being drawn with the key off and I blew the 11 amp fuse in my Fluke 177 meter. Sometimes when I disconnect the battery for 20 minutes or so, the issue goes away for a while but eventually returns. I have replaced nearly one battery per year (and not the cheap ones from Oreillys or Pep Boys) to the tune of 225 - 250 each for Interstate Megatron Plus to Red or Blue top Optimas with the same result in each case being that the car will run great with no problems for the better part of a year and then it's the routine again.
Every time this happens I start reading about the BCM and how they can be glitchy and create issues like the ones that Im having. I have also heard that replacing them with a new one only works some of the time and that they need to be re programmed by a dealer which again is more$$$.
My question is this for all the newer body style electrical guys here; Has anyone here had any problems that are similar to the ones I described and how have you guys dealt with them? Swapped BCM? Other non BCM issues? Keep installing new batteries? Sell the car? Im kind of at my wits end and as I want to fix the problem and not put a band aid on it again.

Ill be very grateful for any advise.
Thanks,
Chris

[hugger6933]

This very week I THOUGHT I had a BCM issue, I had a truck that was T-boned and it was right on the left front door post that required a new cab shell. Once I got the truck all back together[now this is NOT my first rodeo at having the complete truck stripped inside by any means] and all I had working was the directional lights on the dash and a blinking BCM. It ended being the motor to cab ground wire, I had set it on the stud and then went to answer the phone, and never got back to it .sad to say I messed up.
The BCM is vin locked and would cost me with my dealer discount $229.95 at the dealer but yes being vin locked you have to have a dealer or someone with a tech2 to program it for you.
I have also seen problems with ignition switches. Good luck I know it is driving you crazy, but your wife sounds very slow to anger and reaction, Some guys would come home to a new car sitting in the driveway

['63GENIII]

Thanks for the reply hugger. I have noticed this time when she turns off the AC before she turns off the car, it seems to have no problems. I ran an inductive DC amp probe on it the other day and it was only pulling 24 milliamps for about 20 minutes. When I tested it a few days before with my Fluke series amp probe, it blew the 10 amp internal fuse in the meter. That was before we started shutting off the AC. I still believe that its the BCM as sometimes the keyless entry and courtesy lights get funky for a while. This time its seems to be having a problem with the AC.

[1FastBrick]

The body control modules have been known to cause electrical issue like what you describe.

Your ac issue could be caused by the blend door as that is common issue. I have also seen the AC control cause issues as well.

Most shops are either going to throw parts at it with you footing the bill.

What you need to do is monitor the draw and start unplugging circuits 1 at a time until you find it.

['63GENIII]

Just an update on this because this is a problem that became worse over the last 9 years of owning the car. It has been the most difficult troubleshooting job that I have ever come across due to the intermittent nature and symptoms. To be honest, I almost admitted defeat several times and just wanted to get rid of the car. My wife really loves this car and I can't bear to hear "remember that one car that you couldn't fix? Man I really wish we still had that car still" being said by either her or my kids that think I can practically fix anything. Lol.

So three weeks ago, she came home from work saying that she had to get a jump from her co worker. She had thought that she had turned off everything in the car like the radio, AC, dome lights blah, blah, blah. I didn't doubt her. Its just that for the past several years, we've been driving it around nearly paranoid that we won't be able to start it after it sits for a couple of hours. I told her I'd look at it that night again which I did. I know this routine right? Run it for a few minutes, connect my inductive Fluke DC Amprobe, watch it for 2 hours, maybe disconnect the battery and viola' its fixed until the next time right? Wrong.

I went though my routine, watched the parasitic draw drop to .4 amps after 2 hours. Too much. Disconnecting the battery seemed to work though. I put a good charge on the battery (Megatron Plus) and put the probe on it again. All good.

Next morning, I'm at work laying out the job for the day and I get a call at 7:45 from her. She's in tears, freaking out. She explains that while taking the kids to school on a pretty steep, uphill and narrow 2 lane busy thoroughfare , the "battery not charging" warning came on (which has never happened) the car slowed down and died in nearly the middle of the road. This is a road that every soccer mom in a Burb takes their kid to school on, construction trucks on their way to work us and let's not forget that it was also garbage day for that street.

I told her to get herself and the kids out of the car and to a safe place, call AAA and I was also on my way. Luckily a couple of friends came and got the kids to school as they were driving by. At this point, she is not driving this car again until this is fixed.

I got there before AAA, jumped the car with mine and drove it 3 blocks back to the house. It sat for the better part of December.

Im not a guy who likes to or can afford to throw parts at cars or anything for that matter but I was desperate. I ordered a replacement AC Delco BCM off of Amazon for 120$. It showed up on Xmas Eve so I figured Id take the car to the dealer on the next Monday. The wife would have to just drive my little beater CX and I would drive the '63. Monday came and I took it to the dealer only to find that I needed an appointment for them to flash the new BCM. They gave me a 9:00 slot on NYE and said it would be done before the end of the day. That worked for me as I figured it would be the end of my troubles.

At 8:00 on NYE, I brought the car down, explained everything that I could recall about the car to the service advisor and how I just wanted to swap the BCM and have them flash the new module. His response " we can't let you perform any work on the property and I can assure you with almost 100% certainty that its not the BCM and more than likely an aftermarket electronic device that was installed by me. We will need to perform a parasitic draw test first, then we will install the new BCM and flash it according to your VIN". Alright at this point, i get the liability issues and that they need to verify that the BCM is actually bad. Fine. I ask how much. 500$ is the estimate. I almost passed out. I was really thinking more like 100 - 150 for the programming but now I'm over a barrel. I give him the go ahead and take a little comfort that the car should be done by 4:00 p.m. that day.

At 2:30, the advisor calls me (and I'm thinking woo hoo it's ready early) and drops a bomb on me. They got swamped after I left and were not going to be able to touch the car until Monday. Im getting that "over the barrel" feeling again. It's NYE, we have people coming over and this is not the hill I feel like dying on today so I say alright. "But it will be done Monday right?" I ask. He replies " absolutely" but also said that he didn't think it was the BCM.

Today at 2:30, after calling a few times and getting a voicemail each time, I get a call from the service advisor. The car was ready to pick up! I picked up the wife and shot down there. This time a different SA helped us and explained that not only were they able to replicate the current draw that I had, they were not able to use their scanner to get the BCM to shut down any of the loads and said that it had mechanically failed. They installed the new one, flashed it and rechecked the current draw - 60 milliamps which is within spec according to them. The charge for the work 300$ which was 200$ less than quoted, Im happy, the wife is happy and Im hoping that this problem is a done deal. Time will tell.

Lesson learned. Trust your instincts.

['63GENIII]

Damn. Sorry for the long post guys! Guess I got a little excited about the thought of having this thing fixed. Thanks for listening!
Chris

['63GENIII]

Just an update. Since replacing the BCM, I have also replaced the alternator since we would start the car in the morning and although it would start just fine (no more battery draw) the gauge would only read 9 or so volts. I confirmed this with a separate VOM. She would drive the other car during the day. In the afternoon however, the car would start just fine as well but would be charging at 14.2 or so like normal. She would check it every day when she got home. Now I'm at a loss. I resorted to doing what I hate most... throwing parts at a problem. I swapped out the alternator and voila! Its working as normal. Kinda weird though that it wouldn't charge in the morning but would be fine in the evening. Oh well, its fixed for now.

[Boog]

Glad to hear your power draw is fixed.
But don't be surprised to see the charging voltage go up and down. It's normal believe it or not.
Our recently purchased 06 Yukon began showing low voltage while driving at highway speeds. Down and up. It always started just fine. Since my wife is on the highway every weekend I want to do my best to make sure she don't get stranded out there. My first instinct was to replace the alternator. But before I did I did a little search online into charging system problems and found by OE design this alternator fluctuates charging voltage " as needed " as another means of reducing power draw on the engine and increase mpg. This is verified by some GM bulletins.
I've been watching it close and it stays fully charged. Wife's happy. I'm happy.